Cod sursa(job #132945)

Utilizator megabyteBarsan Paul megabyte Data 6 februarie 2008 23:08:15
Problema Radiatie Scor 80
Compilator cpp Status done
Runda Arhiva de probleme Marime 2.04 kb
#include <cstdio>
#include <vector>
#include <algorithm>
#define INF "radiatie.in"
#define OUF "radiatie.out"
#define pb push_back
#define sz(arg) arg.size()


using namespace std;
const int NMAX=16002;
const int MMAX=30002;
const int BIG=2000000000;

struct arc
{
	short x,y;
	int l;
};
struct arc2
{
	short nb;
	int l;
};

short
n,m,k,niv[NMAX]={0},t[NMAX]={0},rang[NMAX]={0},up[NMAX]={0};
int lng[NMAX]={0};
char viz[NMAX]={0};

vector<arc2> a[NMAX];//ARBORE
vector<arc> ed;

void init(short x)
{
	up[x]=x;
	rang[x]=0;
}

short cauta(short x)
{
	if(x!=up[x]) up[x]=cauta(up[x]);
	return up[x];
}

void uneste(short x,short y)
{
	if(rang[x]>rang[y])	up[y]=x;
	else
	{
		up[x]=y;
		if(rang[x]==rang[y]) rang[y]++;
	}
}


bool cmp(arc alfa,arc beta) {return (alfa.l<beta.l);}

void apm()
{
	sort(ed.begin(),ed.end(),cmp);
	short i,nbx,nby,nr;
	arc2 ab;
	
	for(i=1;i<=n;++i) init(i);//componenta conexa in care este i

	i=0;nr=n-1;
	while(nr>0&&i<m)
	{
		while(i<m&&cauta(ed[i].x)==cauta(ed[i].y)) ++i;
		nbx=ed[i].x;nby=ed[i].y;
		ab.l=ed[i].l;
		ab.nb=nby;a[nbx].push_back(ab);
		ab.nb=nbx;a[nby].push_back(ab);
		
		uneste(cauta(nbx),cauta(nby));
		--nr;
	}
}

void dfs(short nd,short lev)
{
	short i,nb;
	viz[nd]=1;niv[nd]=lev;
	for(i=0;i<sz(a[nd]);++i)
	if(!viz[a[nd][i].nb]) 
	{
		nb=a[nd][i].nb;
		t[nb]=nd;lng[nb]=a[nd][i].l;
		dfs(nb,lev+1);
	}
}

int query(short x,short y)
{
	int mx=-1;
	short i,j;
	i=x;j=y;
	if(niv[i]>niv[j])
	{
		while(i>1&&niv[i]>niv[j])
		{
			mx=max(mx,lng[i]);
			i=t[i];
		}
	}
	else
	{
		while(j>1&&niv[j]>niv[i])
		{
			mx=max(mx,lng[j]);
			j=t[j];
		}
	}

	while(i>1&&i!=j)
	{
		mx=max(mx,lng[i]);
		mx=max(mx,lng[j]);
		i=t[i];j=t[j];
	}

	return mx;
}

int main()
{
	FILE *in,*out;
	in=fopen(INF,"r");
	out=fopen(OUF,"w");
	short i,alfa,beta;
	int v;
	arc x;
	fscanf(in,"%hd%hd%hd",&n,&m,&k);
	for(i=0;i<m;++i)
	{
		fscanf(in,"%hd%hd%d",&x.x,&x.y,&x.l);
		ed.push_back(x);
	}

	apm();
	dfs(1,1);
	
	for(i=1;i<=k;++i)
	{
		fscanf(in,"%hd%hd",&alfa,&beta);
		v=query(alfa,beta);
		fprintf(out,"%d\n",v);
	}
	
	fclose(in);fclose(out);
	return 0;
}